Table 2.

Multivariable regression analysis for baseline associations with change in serum phosphate, cFGF23 and iFGF23 at 16 weeks^a

Outcome/variables	Selection method	β coefficient (95% CI)	P-value
Change in serum phosphateb
Treatment: FC versus placebo	Fixed	−0.21 (−0.38 to −0.05)	0.012
Serum phosphate, mg/dL	Fixed	−0.58 (−0.69 to −0.47)	<0.001
eGFR, mL/min/1.73 m2	Stepwise AIC	−0.01 (−0.02 to −0.01)	<0.001
Albumin, g/dL	Stepwise AIC	−0.26 (−0.47 to −0.04)	0.023
Change in cFGF23c,d
Treatment: FC versus placebo	Fixed	−33.8 (−46.3 to −21.3)	<0.001
cFGF23b	Fixed	−0.57 (−0.69 to −0.45)	<0.001
Age, years	Stepwise AIC	−0.86 (−1.41 to −0.32)	0.002
Diabetes: yes versus no	Stepwise AIC	−16.2 (−30.3 to −2.1)	0.025
eGFR, mL/min/1.73 m2	Stepwise AIC	−1.53 (−2.07 to −0.99)	<0.001
Change in iFGF23c,e
Treatment: FC versus placebo	Fixed	−30.2 (−44.4 to −15.9)	<0.001
iFGF23b	Fixed	−0.42 (−0.61 to −0.23)	<0.001
Sex: male versus female	Stepwise AIC	17.7 (3.1–32.3)	0.018
Race: non-white versus whitef	Stepwise AIC	24.4 (9.1–39.8)	0.002
eGFR, mL/min/1.73 m2	Stepwise AIC	−1.03 (−1.78 to −0.28)	0.008
Serum phosphate, mg/dL	Stepwise AIC	−8.5 (−19.1–2.2)	0.122
Log cFGF23	Stepwise AIC	7.0 (−1.5–15.6)	0.109

^aMissing data were imputed using the last observation carried forward method.

^bSensitivity analyses demonstrated stable associations, irrespective of the method for missing data handling or multivariable model selection (Supplementary data, Tables S1 and S2).

^cOwing to non-normal distribution of FGF23, rank transformations were employed.

^dSensitivity analyses demonstrated similar associations among different methods for missing data handling or multivariable model selection (Supplementary data, Tables S3 and S4).

^eSensitivity analyses demonstrated similar associations across most methods for missing data handling or multivariable model selection (Supplementary data, Tables S5 and S6).

^fOf the non-white category, 94.5% were Black or African American.

FC, ferric citrate.